Spatiotemporal isolation of oilseed rape fields reduces insect pest pressure and crop damage.
Abstract
Pest management is essential to maintain agricultural production, but recent shifts in policies and the development of insecticide resistance have restricted the availability of insecticides for pest suppression. Identifying the landscape-level resource requirements of pests to complete their life cycles might unveil new sustainable solutions to regulate their populations and prevent crop damage. We assessed the effects of landscape composition and configuration at different spatial scales on flea beetle densities and crop damage in 56 spring oilseed rape fields sampled over 5 years in Sweden. We considered the cover of non-crop habitats as an aspect of landscape composition and the distances to the host crop and an alternative host crop in the previous year, edge density and crop diversity as aspects of landscape configuration. The distance from spring oilseed rape in the previous year reduced flea beetle densities and crop damage across most species and spatial scales. Edge density reduced the densities of two flea beetle species, predominantly at the 500 m radius landscape scale. The cover of forests and permanent pastures as well as crop diversity in the previous year increased the densities of different species at several, mostly larger (1000-2000 m) spatial scales. Increasing permanent pasture cover at the 500 m scale also increased crop damage. Synthesis and applications: We find that there is no one fits all approach in designing landscapes for flea beetle regulation as habitat use and scales of effect are species-specific for these pests. However, increasing the spatiotemporal isolation of host crop fields is a promising and potentially more general means of disrupting pest populations and reducing crop damage. Considering the ecological traits of the pest species is a possible next step to optimise landscape-based pest management.